What are episcleritis and scleritis?

Episcleritis affects only the episclera, which is the layer of the eye's surface lying directly between the clear membrane on the outside (the conjunctiva) and the firm white part beneath (the sclera). It causes redness and inflammation of the eye, often with discomfort and irritation but without other significant symptoms.

Scleritis affects the sclera and, sometimes, the deeper tissues of the eye. It is much less common than episcleritis. It causes a painful red eye and can affect vision, sometimes permanently.

What's the difference between episcleritis and scleritis?

Episcleritis and scleritis are mainly seen in adults. They can initially look similar but they do not feel similar and they do not behave similarly. Both are slightly more common in women than in men. Both can be associated with other conditions such as rheumatoid arthritis and systemic lupus erythematosus (SLE), although this is more likely in the case of scleritis. Episcleritis does not cause scleritis, although scleritis can lead to associated episcleritis.

Episcleritis is a fairly common condition. It tends to come on quickly. It causes redness - often in a wedge shape over the white of the eye - and mild discomfort. A lot of people might have it and never see a doctor about it. It can occasionally be a little more painful than this and can cause inflamed bumps to form on the surface of the eye. However, it is generally a mild condition with no serious consequences. It usually settles down by itself over a week or so with simple treatment. Episcleritis is often recurrent and can affect one or both eyes.

Episcleritis

Scleritis is much less common and more serious. It tends to come on more slowly and affects the deep white layer (sclera) of the eye. It can spread to affect the adjacent layers around the sclera, including the episclera and the cornea. Scleritis tends to be very painful, causing a deep 'boring' kind of pain in or around the eye: that's how it is distinguished from episcleritis which is uncomfortable but not that painful. The eye is likely to be watery and sensitive to light and vision may be blurred. Scleritis can affect vision permanently. It may involve one or both eyes and is often associated with other inflammatory conditions such as rheumatoid arthritis.

Scleritis

What causes episcleritis and scleritis?

Episcleritis and scleritis are inflammatory conditions. It's not known what triggers the inflammation, which seems to start in the small blood vessels running on the surface of the eye. Both conditions are more likely to occur in people who have other inflammatory conditions, although this is particularly true of scleritis. Scleritis can occasionally be caused by infection with germs such as bacteria, viruses or, rarely, fungi.

Who develops episcleritis and scleritis?

Episcleritis is most common in adults in their 40s and 50s. It is slightly more common in women than in men, and in people who have connective disease disease such as rheumatoid arthritis. About 40 people per 100,000 per year are thought to be affected. However, this is difficult to estimate accurately because many people do not go to a doctor if they have mild episcleritis.

Scleritis is less common, affecting only about 4 people per 100,000 per year. It affects a slightly older age group, usually the fourth to sixth decades of life. It is also slightly more common in women. It is more likely than episcleritis to be associated with an underlying inflammatory condition like rheumatoid arthritis.

What are the symptoms of episcleritis?

There are two types of episcleritis.

The most common type is called diffuse episcleritis and it makes the surface of the eye evenly red, sometimes all over and sometimes in a wedge shape. This picture shows the typical appearance of diffuse episcleritis:

Diffuse episcleritis

Image source: Open-i (Parentin F et al) - see Further reading below

The less common type is called nodular episcleritis. It comes on more slowly and causes inflamed swollen bumps or nodules in the episclera. It is more likely than diffuse episcleritis to be associated with an underlying inflammatory condition.

This picture shows nodular episcleritis in someone's left eye:

Nodular episcleritis

Image source: Open-i (Al-Amry) - see Further reading below

Both forms of episcleritis cause mild discomfort in the eye. The eyes may water a little and the eye may be a little tender when pressure is applied over the red area. However, vision is unaffected and painkillers are not generally needed.

The diffuse type tends to be less painful than the nodular type.

Episcleritis is often a recurrent condition, with episodes occurring typically every few months. Most attacks last 7-10 days, although in the case of nodular episcleritis this can be a little longer.

What are the symptoms of scleritis?

Scleritis causes redness of the eye.

It tends to come on more slowly than episcleritis

As the redness develops the eye becomes very painful. This is a deep boring kind of pain inside and around the eye. It is typically much more severe than the discomfort of episcleritis.

Sometimes the white of the eye has a bluish or purplish tinge.

Vision may be blurred, the eye may be watery (although there is no discharge) and you may find it difficult to tolerate light (photophobia).

There are several types of scleritis, depending on what part of the eye is affected and how inflamed the tissues are:

Anterior scleritis is divided into:

Non-necrotising type (most common). This is divided into:

Diffuse anterior scleritis in which the eye is uniformly red.

Nodular anterior scleritis in which tender nodules develop.

Necrotising type:

With inflammation: this is the most severe form of scleritis. It causes severe pain and tenderness and often causes permanent damage to the eye.

Without inflammation: this rare condition is called scleromalacia perforans and is only seen in patients with long-standing rheumatoid arthritis. The eye is not red or painful but the sclera is gradually thinned.

This picture shows someone with necrotising scleritis in their left eye. This required strong medication to dampen down their immune system:

Necrotising scleritis

Image source: Open-i (Sambhav K et al) - see Further reading below

Posterior scleritis is rare and is also painful although your eye may not be red. Eye movements may be painful and there may be loss of vision.

What is the treatment for episcleritis?

Episcleritis does not necessarily need any treatment. If symptoms are mild it will generally settle by itself.

Many of these conditions can permanently threaten sight and some will require surgical treatment.

What is the long-term outlook (prognosis) for episcleritis and scleritis?

Episcleritis does not usually have any significant long-term consequences unless it is associated with an underlying disease such as rheumatoid arthritis.

The non-necrotising forms of scleritis do not usually permanently affect vision unless the patient goes on to develop uveitis.

Necrotising scleritis with inflammation is the most severe and distressing form of scleritis. It is common for vision to be permanently affected.

When either episcleritis or scleritis occurs in association with an underlying condition like rheumatoid arthritis then its progress tends to mirror that of the underlying disease.

Posterior scleritis is also associated with systemic disease and has a high likelihood of causing visual loss.

It can help to meet and talk to people who have had a similar experience with their eyes: search online for scleritis and episcleritis support groups.

How do I prevent episcleritis and scleritis?

These inflammatory conditions cannot be directly prevented. For people with systemic inflammatory diseases such as rheumatoid arthritis, good control of the underlying disease is the best way of preventing this complication from arising.

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